A stopover is a stop at a transitional point of a journey. It’s typically related to the break between the flight legs of the connecting flight.
Stopover is often used interchangeably with layover but there’s one important difference – the stop duration. While layovers are typically short, stopovers are longer and usually entail leaving the airport.
The rules of stopover and layover duration vary across airlines. Generally, for international trips, a layover is anything from 30 minutes to 24 hours, while a stopover is longer than 24 hours. In domestic travel, a stopover would be anything longer than 4 hours.
Some airlines (e.g., Alaska Airlines, Air Canada, United, Singapore Airlines, etc.) allow their loyalty program members to add stopovers at little or no additional cost when booking award tickets.